How many skill increases are necessary to get a +5 bonus modifier?

I'm trying to raise my strenght attribute, and between each level I fight a lot hand to hand and with blunt weapons just to get as many strength bonus points as possible. Both of those are minor skills, while blade is a major skill, which I also normally increase 2-3 points for each level.

I think during my last level I gained 6 hand to hand points, 5 blunt and 3 blade points, but still the bonus modifier was only +2.

Again, how many skill points are necessary to get +5 points?

I think yu have to do at least 8, i'm not sure. I leveled up my character ONLY using a protect spell and his intelligence modifier was 5.

Thanks, I use a lot of spells all the time, so the intelligence and willpower modifiers are normally always +5.

Hmm... Maybe I'll have to train more strenght than magic if I want +5 for strenght? Maybe the game only gives +5 for the attributes you've trained the most during a level.

I'll just keep fighting summoned skeletons with hand to hand and blunt a lot before I level up next time.